State Key Laboratory of Environment-Friendly Energy Materials, Tianfu Institute of Research and Innovation, School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang, 621010, P. R. China.
College of Science, Hebei University of Science and Technology, Shijiazhuang, 050018, P. R. China.
Adv Mater. 2023 Jun;35(26):e2300771. doi: 10.1002/adma.202300771. Epub 2023 May 5.
Lithium-sulfur (Li-S) batteries are considered as one of the most promising candidates to achieve an energy density of 500 Wh kg⁻ . However, the challenges of shuttle effect, sluggish sulfur conversion kinetics, and lithium-dendrite growth severely obstruct their practical implementation. Herein, multiscale V C MXene (VC) with a spherical confinement structure is designed as a high-efficiency bifunctional promotor for the evolution of sulfur and lithium species in Li-S batteries. Combining synchrotron X-ray 3D nano-computed tomography (X-ray 3D nano-CT), small-angle neutron scattering (SANS), and first-principle calculations, it is revealed that the activity of VC can be maximized by tuning the scale, and the as-attained functions are conducted as follows: (i) the VC acts as the efficient lithium polysulfide (LiPS) scavenger due to the large number of active sites; (ii) the VC exhibits significantly improved electrocatalytic function for the Li S nucleation and decomposition reaction kinetics owing to the scale effect; and (iii) the VC can regulate the dynamic behavior of Li-ions and thus stabilize the lithium plating/stripping effectively on account of the unique ion-sieving effect.
锂硫（Li-S）电池被认为是最有前途的候选者之一，可以实现 500 Wh kg-1 的能量密度。然而，穿梭效应、硫转化动力学缓慢和锂枝晶生长的挑战严重阻碍了它们的实际应用。在此，设计了具有球形限域结构的多尺度 VC MXene（VC）作为高效的双功能促进剂，用于 Li-S 电池中硫和锂物种的演化。通过同步加速器 X 射线 3D 纳米计算机断层扫描（X 射线 3D 纳米 CT）、小角中子散射（SANS）和第一性原理计算，揭示了通过调节尺度可以最大化 VC 的活性，所获得的功能如下：（i）由于大量的活性位点，VC 作为有效的多硫化锂（LiPS）清除剂；（ii）由于尺度效应，VC 对 Li S 成核和分解反应动力学表现出显著提高的电催化功能；（iii）由于独特的离子筛分效应，VC 可以调节锂离子的动态行为，从而有效稳定锂电镀/剥离。
